Coloring matter absorbing near-infrared light and filter for cutting off near-infrared ray

ABSTRACT

A coloring matter absorbing a near-infrared ray which comprises a diimonium salt containing a sulfonimide as an anion moiety, represented by the general formula (1):  
                 
 
wherein R may be the same or different and represents a moiety selected from the group consisting of an alkyl group, a halogenated alkyl group, a cyanoalkyl group, an aryl group, a hydroxyl group, a phenyl group, and a phenylalkylene group, and R 1  and R 2  may be the same or different and each represent a fluoroalkyl group, or together form a fluoroalkylene group. 
The coloring matter absorbing a near-infrared ray is excellent in the resistance to heat and moisture, and thus exhibits an ability of absorbing a near-infrared ray not lowering for a long period of time. A filter for cutting off a near-infrared ray manufactured by using the coloring matter can be advantageously used for wide applications such as a plasma display panel, an optical lens, a glass for an automobile, and a glass for a building material, due to its excellent resistance to heat and moisture.

TECHNICAL FIELD

The present invention relates to a novel near-infrared light absorbingdye obtained from a diimonium salt compound which absorbs light in thenear-infrared spectrum and displays excellent resistance to heat andmoisture and to a near-infrared light blocking filter containing thenear-infrared light absorbing dye.

BACKGROUND ART

Recently, with the rise in demand for large and slim displays, plasmadisplay panels (hereinafter abbreviated as “PDP”) are becoming widelypopular.

Since near-infrared light emitted from a PDP causes electronic equipmentthat use near-infrared remote controls to malfunction, a filter using anear-infrared light absorbing dye to block infrared rays is necessary.

Also, near-infrared light blocking filters are widely used in opticallenses, glass for automobiles and buildings, and the like.

In these applications, the near-infrared light blocking filter isrequired to effectively absorb light in the near-infrared spectrum,while allowing the transmission of visible light, and to possess highresistance to heat and moisture.

Various near-infrared light blocking filters comprising a diimmoniumsalt compound have been proposed (Japanese Patent Application Laid-openNo. 10-180922).

This publication discloses various near-infrared light absorbing dyes ofdiimmonium salt. Of these,N,N,N′,N′-tetrakis{p-di(n-butyl)aminophenyl}-p-phenylene diimmonium saltwhich comprises bis(hexafluoroantimonate) as the anion moiety iscommonly used due to the relatively excellent resistance to heat andmoisture.

However, resistance to heat and moisture of this near-infrared lightabsorbing dye is still inadequate. Specifically, the dye possesses someproblems. For example the dye is decomposed during use therebydecreasing absorbance of near-infrared light. An aminium salt generatedfrom decomposition of the dye causes visible light to be absorbedthereby decreasing transmissivity of visible light and resulting inyellow coloration which degrades color tone.

Furthermore, since this dye comprises a heavy metal as an anion moiety,use of a large quantity of this dye results in environmental pollution.

A first object of the present invention is to provide a novelnear-infrared light absorbing dye with excellent resistance to heat andmoisture, wherein near-infrared light absorbance does not decrease whenused for a long period of time. A second object of the present inventionis to provide a near-infrared light blocking filter possessing excellentresistance to heat and moisture.

DISCLOSURE OF THE INVENTION

As a result of extensive research, the present inventors discovered thata near-infrared light absorbing dye with excellent resistance to heatand moisture can be obtained from a diimonium salt comprising a specificanion moiety, thereby completing the present invention.

Particularly, the present invention provides a near-infrared lightabsorbing dye obtained from a diimonium salt comprising a sulfonimiderepresented by the following formula (1) as an anion moiety.

In the formula, R individually represents an alkyl group, alkyl halide,cyanoalkyl group, aryl group, hydroxyl group, phenyl group, orphenylalkylene group, and R¹ and R² individually represent a fluoroalkylgroup or combine to form a fluoroalkylene group.

In the above near-infrared light absorbing dye, R¹ and R² in the formula(1) preferably individually represent a perfluoroalkyl group having 1-8carbon atoms.

In the above near-infrared light absorbing dye, the fluoroalkylene groupformed from the combination of R¹ and R² in the formula (1) ispreferably a perfluoroalkylene group having 2-12 carbon atoms.

The present invention further provides a near-infrared light blockingfilter comprising the above near-infrared light absorbing dye.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the transmissivity spectrum of the near-infrared lightblocking filter obtained in Example 1.

BEST MODE FOR CARRYING OUT THE INVENTION

The near-infrared light absorbing dye of the present invention isobtained from a diimonium salt comprising a sulfonimide represented bythe above formula (1) as an anion moiety. The near-infrared lightreferred to in the present invention is light with a wavelength in therange of 760-2,000 nm.

There are no limitations to the number of fluorine atoms or carbon atomssubstituted inasmuch as R¹ and R² in the anion moiety shown by theformula (1) individually represent a fluoroalkyl group or combine toform a fluoroalkylene group. R¹ and R² preferably individually representa perfluoroalkyl group having 1-8 carbon atoms. As a preferable exampleof the anion moiety, an anion moiety represented by the followingformula (3) can be given.

In the formula, n and n′ represent an integer from 1 to 8.

n and n′ preferably represent an integer from 1 to 4. As preferablespecific examples, perfluoroalkanesulfonyl groups in which n and n′ arethe same such as bis(trifluoromethanesulfone)imide andbis(pentafluoroethanesulfone)imide; and perfluoroalkanesulfonyl groupsin which n and n′ are different such as pentafluoroethanesulfonetrifluoromethanesulfonimide, trifluoromethanesulfoneheptafluoropropanesulfonimide, and nonafluorobutanesulfonetrifluoromethanesulfonimide can be given. Of these,perfluoroalkanesulfonyl groups in which n and n′ are the same, whereineach of n and n′ is either 1 or 2, such asbis(trifluoromethanesulfone)imide or bis(pentafluoroethanesulfone)imideare particularly preferable in view of near-infrared light absorbance.

Furthermore, a perfluoroalkylene group having 2-12 carbon atoms formedby the combination of R₁ and R₂ can be given as another preferableexample of R₁ and R₂ in the anion moiety shown by the formula (1). As apreferable example of the anion moiety, an anion moiety represented bythe following formula (4) can be given.

In the formula, m is an integer of 2-12.

An anion moiety wherein m is preferably an integer of 2-8 andparticularly preferably an integer of 3, such as1,3-disulfonylhexafluoropropyleneimide shown by the following formula(5) can be given.

The perfluoroalkylene group having 2-12 carbon atoms is preferable dueto increased heat resistance.

In formula (1), R individually represents a substituent selected fromthe group comprising an alkyl group, alkyl halide, cyanoalkyl group,aryl group, hydroxyl group, phenyl group, and phenylalkylene group.

There are no restrictions to the R as long as it is one of the abovesubstituents. R is preferably a linear or branched alkyl group, alkylhalide, cyanoalkyl group or the like having 1-8 carbon atoms, with alinear alkyl group having 2-6 carbon atoms being particularlypreferable.

As particularly preferable specific examples of R in the formula (1), anethyl group, propyl group, butyl group, amyl group, isopropyl group,isobutyl group, isoamyl group, and the like can be given.

Also, as another preferable example of R, a phenylalkylene grouprepresented by the following formula (2) can be given.

In the formula, A represents a linear or branched alkylene group having1-18 carbon atoms and B represents a substituted or unsubstitutedbenzene ring.

In the phenylalkylene group of the formula (2), the alkylene groupparticularly preferably has 1-8 carbon atoms.

Furthermore, the substituted or unsubstituted phenyl group of thephenylalkylene represented by the formula (2) may be substituted by atleast one substituent selected from the group consisting of an alkylgroup, hydroxyl group, sulfonic acid group, alkyl sulfonic acid group,nitro group, amino group, alkoxy group, alkyl halide, and halogen. Anunsubstituted phenyl group is preferable.

As specific examples of the phenylalkylene group, a benzyl group,phenethyl group, phenylpropylene group, phenyl-α-methylpropylene group,phenyl-β-methylpropylene group, phenylbutylene group, phenylpentylenegroup, phenyloctylene group, and the like can be given.

The phenylalkylene group shown by the above formula (2) is used toimprove heat resistance, however, the use of a benzyl group or phenethylgroup is even more preferable.

Next, a method for preparing the near-infrared light absorbing dye ofthe present invention will be described.

A silver sulfonimide acid derivative of the following formula (6) and acompound of the following formula (7) are reacted in an organic solventsuch as N-methyl-2-pyrrolidone, dimethylformamide (hereinafterabbreviated as “DMF”), or acetonitrile at 30-150° C. After separatingthe precipitated silver by filtration and adding a solvent such aswater, ethyl acetate, or hexane, the resulting precipitate is filteredto obtain the near-infrared light absorbing dye of the presentinvention.

In the formula, R, R₁, and R₂ are the same as defined above.

The dye obtained in this manner is combined with a suitable polymerresin and formed into the shape of a film or panel using a known methodsuch as casting or melt extrusion to obtain the near-infrared lightblocking filter of the present invention.

In order to manufacture the near-infrared light blocking filter of thepresent invention by a casting method, the near-infrared light absorbingdye of the present invention is dissolved or dispersed in a solution inwhich a polymer resin and a solvent are dissolved and the resultingsolution is applied to a transparent film of polyester, polycarbonate,or the like, a panel, or glass and dried to obtain a film.

Any known transparent resin may be used as the above polymer resin, withresins such as acrylic resin, polyester resin, polycarbonate, urethaneresin, cellulose resin, polyisocyanate, polyallylate, and epoxy resinbeing preferable.

Also, even though there are no restrictions to the above solvent, anorganic solvent such as methyl ethyl ketone, methyl isobutyl ketone,toluene, xylene, tetrahydrofuran, and 1,4-dioxane, or a mixture of thesesolvents may be used.

On the other hand, when a melt extrusion method is used to manufacturethe near-infrared light blocking filter of the present invention, thenear-infrared light absorbing dye of the present invention is melted andmixed in the polymer resin and extruded in the shape of a panel.

Any known transparent resin may be used as the above polymer resin, withresins such as acrylic resin, polyester resin, and polycarbonate beingpreferable.

In manufacturing the near-infrared light blocking filter of the presentinvention, the near-infrared light absorbing dye may be used alone or,in order to improve the blocking performance of near-infrared lightsnear a wavelength of 850 nm, may be used in combination with a known dyesuch as a phthalocyanine or a dithiol metal complex. Also, in order toimprove lightfastness, ultraviolet absorption dyes such as benzophenoneand benzotriazole may be added. Furthermore, when necessary, aconventional dye that absorbs visible light may be added in order toadjust the color tone.

The near-infrared light transmissivity of the near-infrared lightblocking filter of the present invention can be controlled by adjustingthe mixed ratio of the near-infrared light absorbing dye of the presentinvention and the polymer resin. Although not specifically limited, thenear-infrared light absorbing dye is preferably used in an amount in therange of 0.01-30 wt % (hereinafter abbreviated as “%”) for the totalamount of the polymer resin. If the near-infrared light absorbing dye isused in an amount less than 0.01%, the near-infrared light blockingcapability is unsatisfactory, and if more than 30%, transmissivity ofvisible light declines. The near-infrared light absorbing dye isparticularly preferably used in an amount of 0.05-30% for the totalamount of the polymer resin.

The near-infrared light absorbing dye of the present invention asdescribed above excels in resistance to heat and moisture, does not losenear-infrared light absorbance over a long period of time, and, due tothe absence of heavy metals, does not adversely affect the environment.

Furthermore, the near-infrared light blocking filter comprising thenear-infrared light absorbing dye of the present invention can be usedin a wide variety of uses that require blocking of near-infrared light.As specific examples, the near-infrared light blocking filter can beused in PDP's and glass for automobiles and buildings, and suitably usedin PDP's.

Furthermore, the near-infrared light absorbing dye of the presentinvention may also be used as a dye or quencher for optical recordingmedia such as a CD-R or DVD-R.

EXAMPLES

The present invention will be described in more detail by way ofExamples which should not be construed as limiting the presentinvention. In the examples, “wt %” is indicated as “%” and “parts byweight” is indicated as “parts”.

Example 1

(1) 10 parts of silver bis(trifluoromethanesulfone)imidate and 11.8parts of N,N,N′,N′-tetrakis(p-dibutylaminophenyl)-p-phenylene diaminewere added to 100 parts of DMF, the mixture was reacted at 60° C. forthree hours, and the silver produced from the reaction was separated byfiltration.

Next, 200 parts of water was added to the filtrate and the precipitatewas separated by filtration and dried to obtain 15.7 parts ofbis(trifluoromethanesulfone)imidateN,N,N′,N′-tetrakis(p-dibutylaminophenyl)-p-phenylene diimmonium as anear-infrared light absorbing dye. This near-infrared light absorbingdye had a maximum absorption wavelength (hereinafter abbreviated as“λmax”) of 1,074 nm and a molar absorption coefficient of 105,000[L.mol⁻¹.cm⁻¹]. Differential thermal analysis confirmed that thenear-infrared light absorbing dye had a melting point of 191° C. and adecomposition point of 310° C.

(2) Next, 2 parts of the near-infrared light absorbing dye was dissolvedin a solution containing 6 parts of an acrylic lacquer resin (ThermolacLP-45M, registered trademark of Soken Chemical & Engineering Co., Ltd.),25 parts of methylethyl ketone, and 13 parts of toluene. This solutionwas applied to a commercially available polymethacrylic resin film(thickness: 50 μm) using a 200 μm bar coater. The solution was dried at100° C. for three minutes to obtain the near-infrared light blockingfilter of the present invention.

(3) The heat resistance of the filter maintained in an atmosphere at 80°C. was examined and the percentage of the molar absorption coefficientafter a predetermined period of time was calculated using the initialmolar absorption coefficient at a wavelength of 1,000 nm as 100% todetermine the residual ratio of the near-infrared light absorbing dye.

Next, transmissivity at a wavelength of 480 nm was measured aftermaintaining the filter in an atmosphere at 80° C. for a predeterminedperiod of time. The results are shown in Table 1.

The moisture resistance of the filter maintained in an atmosphere of 60°C. and 95% RH was examined and the residual ratio and transmissivity ofthe near-infrared light absorbing dye at a wavelength of 480 nm wasdetermined in the same manner as in the heat resistance examination. Theresults are shown in Table 2.

Example 2

Bis(trifluoromethanesulfone)imidateN,N,N′,N′-tetrakis(p-dibutylaminophenyl)-p-phenylenediimmonium wasobtained in the same manner as in Example 1 except for using 12.6 partsof silver bis(pentafluoroethanesulfone)imidate instead of 10 parts ofsilver bis(trifluoromethanesulfone)imidate. This near-infrared lightabsorbing dye had a λmax of 1,074 nm and a molar absorption coefficientof 101,000 [L.mol⁻¹.cm⁻¹], a melting point of 185° C., and adecomposition point of 301° C.

A near-infrared light blocking filter was manufactured and the heat andmoisture resistance of the filter was examined in the same manner as inExample 1. The results are shown in Tables 1 and 2.

Comparative Example

Bis(hexafluoroantimonate) N,N,N′,N′-tetrakis{p-di(n-butyl)aminophenyl}-p-phenylene diimmonium was obtained in thesame manner as in Example 1 except for using 8.9 parts of silverhexafluoroantimonate instead of 10 parts of silverbis(trifluoromethanesulfone)imidate. This near-infrared light absorbingdye had a λmax of 1,074 nm and a molar absorption coefficient of 101,000[L.mol⁻¹.cm⁻¹], a melting point of 185° C., and a decomposition point of301° C.

A near-infrared light blocking filter was manufactured and the heat andmoisture resistance of the filter was examined in the same manner as inExample 1. The results are shown in Tables 1 and 2. TABLE 1 HeatResistance Dye residual ratio (%) 480 nm transmissivity rate (%) Periodof Comparative Comparative time Example 1 Example 2 Example Example 1Example 2 Example Initial 100 100 100 77.6 78.1 76.1 After 120 hours96.5 95.8 89.7 77.2 77.5 75.6 After 240 hours 94.4 93.1 85.6 77.3 76.172.8 After 500 hours 92.7 91.8 81.2 76.7 75.8 71.4

TABLE 2 Moisture Resistance Dye residual ratio (%) 480 nm transmissivityrate (%) Period of Comparative Comparative time Example 1 Example 2Example Example 1 Example 2 Example Initial 100 100 100 76.7 76.1 76.7After 120 hours 95.9 94.8 88.9 75.0 74.0 70.3 After 240 hours 94.4 92.984.8 74.5 72.9 68.4 After 500 hours 91.2 89.8 80.0 73.5 70.8 65.4

The results show that the conventional near-infrared light absorbing dyeof the comparative example possesses low resistance to heat andmoisture, decomposes over time, and has a low absorbance index ofnear-infrared light near a wavelength of 1,000 nm. Furthermore, anaminium salt compound and the like generated from decomposition absorbsvisible light near a wavelength of 480 nm thereby causing transmissivityof visible light to degrade and results in yellow coloration whichdegrades color tone.

In comparison, the near-infrared light blocking filters comprising thenear-infrared light absorbing dyes obtained in Examples 1 and 2 possessexcellent resistance to heat and moisture, only slightly degradednear-infrared light absorption performance, and coloration due todecomposition of the dye only with difficulty.

Example 3

10 parts of N,N,N′,N′-tetrakis(p-aminophenyl)-p-phenylenediamine, 55parts of iodated benzyl as a substituent raw material, and 30 parts ofpotassium carbonate were added to 100 parts of DMF solvent and themixture was reacted at 120° C. for ten hours while stirring.

Next, 500 parts of water was added to the reaction solution and theprecipitate was separated by filtration, washed with water, and dried at100° C. to obtain 23.1 parts ofN,N,N′,N′-tetrakis(p-dibenzylaminophenyl)-p-phenylenediamine.

23.1 parts of the above reaction product and 32.5 parts of silverbis(trifluoromethanesulfone)imide as an anion raw material were added to200 parts of DMF solvent, the solution was reacted at 60° C. for threehours with stirring, and the produced silver was separated byfiltration.

Next, 200 parts of water was added to the obtained filtrate and theprecipitate was separated by filtration, washed with water, and dried at100° C. to obtain 32.2 parts of the near-infrared light absorbing dye ofthe present invention. The dye obtained wasbis{bis(trifluoromethanesulfone)imidate}N,N,N′,N′-tetrakis(p-dibenzylaminophenyl)-p-phenylenediimmoniumshown by the formula (1) wherein all R substituents are benzyl groups.

Example 4

The dye of the present invention,bis{bis(trifluoromethanesulfone)imidate}N,N,N′,N′-tetrakis(p-diphenethylaminophenyl)-p-phenylenediimmonium,was obtained in the same manner as in Example 3 except for using 58.5parts of iodated phenethyl as a substituent raw material.

Example 5

The dye of the present invention,bis{bis(trifluoromethanesulfone)imidate}N,N,N′,N′-tetrakis{p-di(4-fluorinated)benzylaminophenyl}-p-phenylenediimmonium, wasobtained in the same manner as in Example 3 except for using 59.5 partsof iodated (4-fluorinated)benzyl as a substituent raw material.

Example 6

First, 3.5 parts of 1,3-disulfonhexafluoropropyleneimidate (manufacturedby JEMCO Inc.) was dissolved in 20 parts of water, 1.4 part of silveroxide (I) was added, and the mixture was reacted and concentrated bydrying to obtain 4.8 parts of silver1,3-disulfonylhexafluoropropyleneimidate.

The near-infrared light absorbing dye of the present invention,bis(1,3-disulfonylhexafluoropropyleneimidate)N,N,N′,N′-tetrakis(p-diphenethylaminophenyl)-p-phenylenediimmonium,was obtained in the same manner as in Example 3 except for using 58.5parts of iodated phenethyl as a substituent raw material and 33.5 partsof silver 1,3-disulfonylhexafluoropropyleneimidate as an anion rawmaterial.

Example 7

The near-infrared light absorbing dye of the present invention,bis(1,3-disulfonylhexafluoropropyleneimidate)N,N,N′,N′-tetrakis(p-dibutylaminophenyl)-p-phenylenediimmonium,was obtained in the same manner as in Example 3 except for using 46.4parts of iodated butyl as a substituent raw material and 33.5 parts ofsilver 1,3-disulfonylhexafluoropropyleneimidate as an anion rawmaterial.

Example 8

The λmax and molar absorption coefficient of the near-infrared lightabsorbing dyes obtained in Examples 3-7 were measured. The results areshown in Table 3. (The unit of molar absorptivity shown in Table 3 is[L.mol⁻¹.cm⁻¹].)

A near-infrared light blocking filter was manufactured and the heat andmoisture resistance of the filter was examined in the same manner as inExample 1. The results are shown in Tables 4 and 5. TABLE 3 PropertyValue Ex- Molar am- λmax absorption ple Near-infrared light absorbingdye (nm) coefficient 3 Bis{bis(trifluoromethanesulfone)imidate}- 1059104000 N,N,N′,N′-tetrakis(p-dibenzylamino- phenyl)-p-phenylenediimmonium4 Bis{bis(trifluoromethanesulfone)imidate}- 1074 104000N,N,N′,N′-tetrakis(p-diphenetylamino- phenyl)-p-phenylenediimmonium 5Bis{bis(trifluoromethanesulfone)imidate}- 1051 103000N,N,N′,N′-tetrakis{p-di(4- fluorinated)benzylaminophenyl}-p-phenylenediimmonium 6 Bis(1,3-disulfonylhexafluoropropyleneimidate)-1073 104000 N,N,N′,N′-tetrakis(p-diphenethylamino-phenyl)-p-phenylenediimmonium 7Bis(1,3-disulfonylhexafluoropropyleneimidate)- 1073 104000N,N,N′,N′-tetrakis(p-dibutylaminophenyl)- p-phenylenediimmonium

TABLE 4 Heat Resistance Dye residual ratio (%) 480 nm transmissivityrate (%) Example Example Period of time 3 4 5 6 7 3 4 5 6 7 Initial 100100 100 100 100 77.2 77.9 77.2 77.9 77.3 After 120 hours 98.7 99.2 98.799.1 98.8 76.8 77.4 76.9 77.5 76.8 After 240 hours 97.2 98.0 97.4 98.297.7 75.8 76.6 76.0 76.7 75.7 After 500 hours 94.8 96.0 95.2 96.3 94.575.3 76.2 75.5 76.3 75.2

TABLE 5 Moisture Resistance Dye residual ratio (%) 480 nm transmissivityrate (%) Example Example Period of time 3 4 5 6 7 3 4 5 6 7 Initial 100100 100 100 100 77.1 77.9 77.2 77.9 77.3 After 120 hours 98.6 99.0 98.598.7 98.4 76.1 77.4 76.5 77.4 76.3 After 240 hours 96.6 97.4 96.5 97.596.5 74.0 76.2 74.8 76.5 74.1 After 500 hours 92.9 94.8 93.3 95.1 92.673.1 75.8 73.8 75.9 72.9

As shown in Tables 4 and 5, the near-infrared light blocking filterscomprising the near-infrared light absorbing dyes obtained in Examples3-7 possess excellent resistance to heat and moisture, only slightlydegraded near-infrared light absorption performance, and coloration dueto decomposition of the dye only with difficulty.

INDUSTRIAL APPLICABILITY

The near-infrared light absorbing dye of the present invention excels inresistance to heat and moisture, does not lose near-infrared lightabsorbance over a long period of time, and, due to the absence of heavymetals, does not adversely affect the environment.

The near-infrared light blocking filter comprising the near-infraredlight absorbing dye of the present invention can be used in a widevariety of uses including PDP's and glass for automobiles and buildings,in particular PDP's.

Furthermore, the near-infrared light absorbing dye of the presentinvention may also be used as a dye or quencher for conventional opticalrecording media such as a CD-R or DVD-R.

1. A near-infrared light absorbing dye obtained from a diimonium saltcomprising a sulfonimide represented by the formula (1):

wherein, R individually represent an alkyl group, alkyl halide,cyanoalkyl group, aryl group, hydroxyl group, phenyl group, orphenylalkylene group, and R¹ and R² individually represent a fluoroalkylgroup or combine to form a fluoroalkylene group.
 2. The near-infraredlight absorbing dye of claim 1, wherein R¹ and R² individually representa perfluoroalkyl group having 1-8 carbon atoms.
 3. The near-infraredlight absorbing dye of claim 2, wherein R¹ and R² both represent atrifluoromethyl group or both represent a pentafluoroethyl group.
 4. Thenear-infrared light absorbing dye of claim 1, wherein R¹ and R² combineto form a perfluoroalkylene group having 2-12 carbon atoms.
 5. Thenear-infrared light absorbing dye of claim 4, wherein R¹ and R² combineto form a hexafluoropropylene group.
 6. The near-infrared lightabsorbing dye of claim 1, wherein R represents a linear or branchedalkyl group having 1-8 carbon atoms, an alkyl halide, or a cyanoalkylgroup. 7-9. (canceled)
 10. The near-infrared light absorbing dye ofclaim 2, wherein R represents a linear or branched alkyl group having1-8 carbon atoms, an alkyl halide, or a cyanoalkyl group.
 11. Thenear-infrared light absorbing dye of claim 3, wherein R represents alinear or branched alkyl group having 1-8 carbon atoms, an alkyl halide,or a cyanoalkyl group.
 12. The near-infrared light absorbing dye ofclaim 4, wherein R represents a linear or branched alkyl group having1-8 carbon atoms, an alkyl halide, or a cyanoalkyl group.
 13. Thenear-infrared light absorbing dye of claim 5, wherein R represents alinear or branched alkyl group having 1-8 carbon atoms, an alkyl halide,or a cyanoalkyl group.
 14. The near-infrared light absorbing dye ofclaim 1, wherein R represents a phenylalkylene group of the followingformula:

wherein, A represents a linear or branched alkylene group having 1-18carbon atoms and B represents a substituted or unsubstituted benzenering.
 15. The near-infrared light absorbing dye of claim 2, wherein Rrepresents a phenylalkylene group of the following formula:

wherein, A represents a linear or branched alkylene group having 1-18carbon atoms and B represents a substituted or unsubstituted benzenering.
 16. The near-infrared light absorbing dye of claim 14, wherein Rrepresents a benzyl group or phenethyl group.
 17. The near-infraredlight absorbing dye of claim 15, wherein R represents a benzyl group orphenethyl group.
 18. A near-infrared light blocking filter comprisingthe near-infrared light absorbing dye of claim
 1. 19. A near-infraredlight blocking filter comprising the near-infrared light absorbing dyeof claim
 2. 20. A near-infrared light blocking filter comprising thenear-infrared light absorbing dye of claim
 3. 21. A near-infrared lightblocking filter comprising the near-infrared light absorbing dye ofclaim
 4. 22. A near-infrared light blocking filter comprising thenear-infrared light absorbing dye of claim
 5. 23. A near-infrared lightblocking filter comprising the near-infrared light absorbing dye ofclaim
 6. 24. A near-infrared light blocking filter comprising thenear-infrared light absorbing dye of claim
 10. 25. A near-infrared lightblocking filter comprising the near-infrared light absorbing dye ofclaim
 11. 26. A near-infrared light blocking filter comprising thenear-infrared light absorbing dye of claim
 12. 27. A near-infrared lightblocking filter comprising the near-infrared light absorbing dye ofclaim
 13. 28. A near-infrared light blocking filter comprising thenear-infrared light absorbing dye of claim
 14. 29. A near-infrared lightblocking filter comprising the near-infrared light absorbing dye ofclaim
 15. 30. A near-infrared light blocking filter comprising thenear-infrared light absorbing dye of claim
 16. 31. A near-infrared lightblocking filter comprising the near-infrared light absorbing dye ofclaim 17.